1. The missing boy was last seen ____ near the river. A. playing B. to be playing C. play D. to pl

1. The missing boy was last seen __A__ near the river.
A. playing B. to be playing C. play D. to play

不是“被看见”吗？为什么不选B？

8. You can’t have the horse ___C__ all the way. It’s too hot.
A. run B. to run C. running D. to be running

让马去跑 意思是让某人做某事 不是用have sb do么 为什么不选A

1. 考点: see sb. doing sth. 看见某人正在做某事
变成被动语态后, 就成了: sb. be seen doing sth.
不能用sb. be seen to be doing 哟！
因此此题选A不选B。

8. 注意这两者的区别:
have sb. do sth. 让某人做某事.(某人做了某事, 强调动作已结束)
have sb. doing sth. 让某人一直做某事. (强调动作的延续性, 动作还未结束)
此句的意思是: 不要让马一直跑, 天气太热了.
由句意可知, 这儿是强调动作的延续性,因此应选C而不是A.

see sb doing 看到某人正打做什么 see sb do 看某人做某事的整个过程 这是see 的两个用法 所以答案是a